1. Field
The methods, systems, objects, features, and advantages of the present invention generally relate to transformer coupled position sensing and simulation thereof. In particular they relate to providing universal sensing, control, and simulation of synchros, resolvers, linear variable differential transformers (LVDT), and rotary variable differential transformers (RVDT).
2. Description of the Related Art
Converting angular rotation or linear displacement to an electrical signal may be performed by an AC transducer. Types of transducers include synchros, resolvers, and linear/rotary variable differential transformers (LVDTs/RVDTs). They can be used in a variety of applications, such as an inertial navigation reference unit (gyro or compass), an automatic direction finder (ADF), an omni range system, distance measurement equipment, cockpit indicators, landing-gear positioning and control, various industrial applications, motor control, position detection, machine tool control, oil field exploration, navigation, flight simulation, and many other relative position detection applications.
Synchros, resolvers, LVDTs, and RVDTs have been used in a variety of military and commercial systems for many years, because of the high degree of reliability when difficult environment conditions exist. The simplicity of operation when combined with superior reliability makes these non-contact position sensors a very attractive component of industrial control, operation, simulation and the like. In an example, a resolver or synchro in an automatic direction finder is used to provide an electrical signal that may drive an indicator. As an aircraft turns, the amount of coupling in the transducer changes proportionally. There are many other examples of use of these relative position sensing technologies that populate the known art.
While synchros, resolvers, LVDTs, and RVDTs output an electrical signal, the output signal typically must be converted to a digital signal for processing, and other operations associated with computerized motion sensing, control, simulation and the like. Digital converters are commonly configured with hardware that is tailored to meet voltage and frequency requirements associated with particular synchro, resolver, LVDT, or RVDT implementation specifications. Hardware-tailoring is commonly implemented through selection of certain combinations of electrical components that support the implementation specifications. However, there are a wide variety of implementation specifications across even a single industry, such as avionics. Therefore to offer products that can be sold to even a single customer in a single industry, a converter supplier may have to offer a variety of differently tailored converters. Consequently, each unique implementation requires a correspondingly uniquely tailored converter, resulting in increases in converter ordering complexity, service parts stocking, installation and maintenance procedures, and the like. Also, while hardware-tailored converters may facilitate digital conversion, they cannot be used with different synchro, resolver, LVDT, and/or RVDT implementations. Therefore as new implementation requirements arise, new hardware-tailored converters must be designed, tested, and offered for sale, thereby slowing down converter customer development cycles. Hardware-tailored converters increase costs throughout the supply chain—including manufacturers, distributors, integrators, customers, maintenance suppliers, and the like. There are certain implementations that hardware-tailored converters cannot support, such as calibration and test. Because the hardware is tailored to a particular implementation specification, determining a degree of calibration within the particular implementation specification cannot be achieved without changing the hardware, such as using a dedicated calibration or test device.
In an example, hardware tailoring may include using differential sensing circuits—such as differential amplifiers to produce a measurable analog signal from the synchro, resolver, LVDT, or RVDT. Signal amplification is quite common in these applications because without a measurable signal, digital conversion is not possible. However, a 4-wire implementation requires different sensing hardware than a 5-wire or a 6-wire implementation. Consequently, even if frequencies and voltages are identical for each of the 4, 5, and 6-wire implementations, uniquely tailored differential sensing circuitry must be provided.